1. Field of the Invention
This invention relates to extendible boom structures and, more particularly to boom structures having articulated segments which can be coiled for storage.
2. Prior Art
Mechanisms for storing the elements of an extendible, segmented boom structure in a coiled configuration on a reel are known in the prior art. For example, U.S. Pat. No. 3,179,267 discloses a plurality of segment links, each segment having a different shape. The segments taper inwardly from the inner to the outer end of the boom so that the segments are not uniform and the outer segments have a smaller cross-sectional area. The segments are joined together with heavy-duty pin joints which, in operation, carry the loading forces exerted on the boom. The segments are coiled for storage in a magazine and guided within the magazine by tracks engaging the ends of the pins joining the segments. This type of boom provides no additional mechanisms or structural elements for strengthening the boom so that the capacity of the boom is limited by the strength of the smallest end segments. The segments are not provided with cables to assist the boom in carrying a load. If this type of boom is inverted, it will collapse and cannot be used in an inverted position since the pivot joints between segments are pin joints, no provisions are made for protecting the joints when they are overloaded. Nothing in this type of boom design provides additional strength for handling side loads.